Hydrocarbon conversion



P 1952 v. o. BOWLES ET AL 2,609,332

HYDROCARBON CONVERSION Filed Aug. 25, 1948 E'levator Calciner ATT Y the:reaction zone. I

Patented Sept. 2, 1952 ration of- Delaware A;pplicat;ion.August25,1948;SerialNo;46,-167 l "JIhis invention relates.toranlimprovedlniethod of. producingcoke-andis more particularly a con-;tinuation-in-part vof our "application Serial ,No.

Idond-Lin". favor. or -app1icatiorl!.'Serial No; .3174? BClMms.(cocoa-14) fi1e'd'January'22, "1948, now Patent Nofasersse.

In accordance with ourprior invention, we have 'disclosedl-a newmethodof lproducingl'oke'.byithe 7 continuous conversion .'of {lh.eav'yhydrocarbons such as residues'iwhi'ch arethebypro'ducts of ,crude'oil'dist'illatiomor,tars which are vbio-Prodrappliedjto'andcarried by:the coke particles during the continuous movement of the columndownwardly, and when these conditionsiare' met there is no adherencebetween particles ofisufficient extentto interfere with 'thei'freeflowing -character of the' column. j p

"Our invention has also utilized the technique of avoiding the} addition:Of heatjto thecoking operation except inthe introduction of the?preheated oilcharge and thecokepa'rtifcles so that maximum temperatureis at the'topof the'reactionzone-and so that there Will -be no tendencyof 'the vapors' to condense asthey move upwardly andflareremoved. Thereis also no dilutionirom products of a combustion as -air is excludedfrom fliInxour Vprior applications it was "contemplated that thereheating would :be accomplishedtby introducing air into asealed'reheating zone with a partial combustion of'some of the cokeandthe substantially complete vfreeing-of the volatiles containedtherein. While it was found that such operation resulted in a highlydense and superior form.of coke, it has. now u beenfound that .moreefi'ective andamore economical control can-be accomplished when onlytheremoved netproduct is so'calcined. T V p v .The present invention hasforits principal "object,tthe productionof high quality calcined coke'ofdense nature containing substantially no asha'nd' having a low'volatile" content.

A further object of the invention is to'provide an improved method ofcalcining coke in a con- 'tinuous contact coking unit wherebysubstantial heat economiesare obtained by the handling of "dry coke-atelevated'temperatures.

. "$32 Y a i. Itlisan I additional. object r th ,inve'ntionfftoproi'r'iide' improved .apparatusfi for controllingnlthe size of thecolumn'particles and more'efficie'ntly reheating said particles in a lcontinuous Lcontact ieo in umt, o i 1 E L Fiirther objects andadvantages .ofjour' invenlt io'n will appear from the followingdescription of Ta"preferre'd"form of, embodiment thereotut'akenlinconnection .with'fthe attached-"drawing which" is al 'rdiagr'ammaticelevational' view of the. essential parts are contin ous contact coking.unitfor'the production of calcined coke. I a p In accordance withapreferrd form .oftembodimentfo'f our invention,"the reactor generallyindijcated "at H! is a suitable sealed vessel through jwhichcoke iscontinuously fed through the inlet 12! and is passed downwardly solelyby'igravity over thedistributing b'aifie I 4,1'adjacent' which'jtheliquid hydrocarbon charge introduced a't 1'6 is'disr ted by.the'distributo'r'"elements rs, T'The e11 "preferably heated tea-suitable1 minimum temiperature, as inheater' I'5, whichai'dsin its partialivaporizationl in contact with the companions. "Ihesecolumnar"flowingparticles are maintained at atmo'derate temperature to accomplish avaporization or; a desired" portion of the, char-gel and the r man-on"ofai'dry jcoke coating jjon'i th ticl'e's" as ftheymovedownwardly totheoutle f'Thisoutlevmayf'have asteam seal-lineill'; v

jj ItfiSOll'r experiencethatiairee flowingfgravity 'paclgedi'mass can"successfully 'car'r'yj and co vent to dry cokeand '"vapors' up "to jabout 5 its iv-eight of hydrocarbons "of '"jthe fresidualjgt .pe,*wherethediscrete cokepa'rticles vary in 'sizefro'm -As th'e contactparticles move-through thereactor' 1 9; uniform flow' isnecessary-whichmay Joe accomplishedby 'fiow "c'o'ntrol plates2Z "of any well knowntype. 'Uni'form' flow assureyeven- :ness' of charge distribution anduni'formresidence time, it being known that the viscosity of the chargeat the elevated temperature is about one tenth that of water. As thecoating or particle growth thus is of the order of only 0.001 inch perpass, it will be apparent that repeated passage through the reactor iscontemplated. This is accomplished by discharging the coatedparticlesthrough outlet control valve 23 into elevator inlet 24, and. with anycoke make-up from line 24a, into a suitable elevator 25 which carriesthe particles to the elevator outlet 26.

In accordance with our invention, we prefer to pass all of the contactparticles into a classifier generally indicated at 28 which may be of'any suitable type and which will discharge a uniform quantity of coke ofdesired size through line 34 for return to the system. Fines may beremoved at 30 and the larger size particles removed as net productthrough line 32. If found desirable, some of this net product from line32 may be passed through a crusher 33 and returned to the coke make-upline 24a for recycling. t

Although the reaction is both exothermicand endothermic and nearlybalanced in reactor in 'where the conversion is to dry coke, there issome heat loss by radiation and otherwise, and the particles which areto be returnedto the reactor 4 the reheater 35 to the stack 43. It is ofcourse understood that appropriate waste heat recovery means may also beused to aid in the cooling of the products of combustion.

In accordance with our present disclosure, we have efiectivelysegregated the reheating and reaction zones and provided for the passageof the contact particle material through the elevator 25 While saidmaterial is in its coolest condition. The reduction in temperature atthis point decreases the elevator operation cost. Furthermore only thenet coke removed through the line 60 is calcined, with some economy inH] are conveniently passed through the reheater 35. This is a separatesealed chamber connected with the classifier 28 through the inlet line34. The upper partof the reheater 35 is provided with a series ofradiant heat burners, generally indicated at 38, which are supplied bymanifolds 40 with fuel gas from line 4| and air from line '42; Thecontinuously changing surface layer formed by the cokeparticles as theyenter the reheater 35 is thus continuously brought up to .the desiredtemperature. Products of combustion flowdownwardly and are dischargedto. stack line 43 from vapor collecting channel 44. The reheated cokeparticles then pass through seal pipe 45, having steam purge line 46, tothe inlet 12 to the reactor ID, as previously mentioned. We have foundthat the continuous, and repeated-passage of coke particles through thereheater and the reactor tends to create a highly dense, non-porous cokewhich appears to, be radically different from the ordinary porous coalcoke or petroleum coke known to the industry. Tofurther improve thequalities of the coke productwe find it desirable to pass it.,;throughthe calciner 48 and subject it to controlled. calcining with airintroduced at 49.-- This novel product, which possesses great utility asa heat exchange medium and for metallurgical purposes, is described morefully and claimed in our copending application, Serial No. 46,168 filedAugust 25, .1948.

,Thehcoke normally leaving the classifier 28 through the outlet 32 isalready in ahighly heated condition, the temperature of which may rangefrom 900. to 1,000 E, is substantially all of a size, and is, of course,completely free of any liquid. In the calciner 48 it is possible torapidly bring the coke particles up to.-a temperature of, 2,000 F. andthe products of the combustion may be carried through the line 50 tothe, upper partof the reheater 35. r r

In view of the fact that the products of combustion leave the calciner48 at approximately 2,000 F. they can be effectively used for reheat-.ing of the bed particles before they enter the reactor H]. In addition,the combustion gases .are substantially cooled in their passage throughoperation, thereby avoiding the need of high temperature operations inconnection with all of the coke.

A typical unit for converting 18 A. P. 1. Mid Continent reduced crude atthe rate of 4500 bbl. per day, and producing major yields of dry cokewill circulate from 200 to 300 tons per hour of contact material and thereactor may be approximately 16' in diameter with a 28' bed andthereheater may be approximately 16' in diameter and have a 14' column,With equilibrium coke the solids feed is from 9 to 15 times the oil feedby weight.

v Inasmuch as calcining is largely for the purpose of removing volatilematerial, and only high temperatures are required, this may beaccomplished either by combustion or by radiation from a suitableheatfsource It is to be understood that either type may be used asconditions require. It isof course also possibleto remove partiallycalcined coke directly from the system if the extra treatment is notrequired,v

While we have shown and described a preferred form of embodiment of our,invention we are aware that modifications maybe rnadethe'reto andwetherefore desire a broad interpretation of our invention within thescope and spirit ofv the carbons in liquid phase, converting thespreadcharge into solid dry coke adhering to the coke particles of saidbed and vaporous lighter hydrocarbons, removingfsaid vaporoushydrocarbons from said reaction space, recycling a'substantially uniformquantity of said coke particles having solid dry adhered coke to areheating space sealed off from said reaction space, continuouslyremoving a net coke product corresponding in amount to the cokeproducedin the reaction space, calcining said net product coke in the presenceof an oxygen containing gas, introducing ,theprodnets of combustionfromthe calcining step into the reheating space to reheat th recycled. cokeparticles therein, exposing the. coke particles as they are'fed intothereheating space to the heating effect of radiant heat burners,collecting and removing the products of combustion from the reheatingspace, and passing the reheated coke flow of products of combustion fromthe reheating space to the reaction space.

In a continuous contact method of converting heavy hydrocarbon oils intocoke and lighter hydrocarbons which comprises continuously andrepeatedly passing a column of gravity packed preheated coke particlesthrough a sealed reaction space solely by gravity, introducing a heavyhydrocarbon oil charge largely in liquid phase into the upper part ofsaid coke column while so controlling the rate of movement of thecolumn, the rate of feed of the charge per unit of column volume, thetemperature of the entering coke particles and the distance throughwhich the column moves before leaving the reaction space that theadhering liquid carried by the column particles will be converted tolighter hydrocarbon vapors and a dry, non-adherent coke coating on theparticles, removing said lighter hydrocarbon vapors from the reactionspace, discharging said coke coated particles from the reaction space,reheating and returning a substantially uniform quantity of cokeparticles to the reaction space, continuously removing a net cokeproduct substantially equivalent to the amount produced by theconversion, subjecting the net coke product thus removed to a calciningoperation in the presence of a gas, whereby the net coke product israised to a substantially higher temperature than that in the reactionspace, and cooling the gas from the calcining operation by contact withthe said coke particles returning to the reaction space.

3. The method as claimed in claim 2, including the steps of classifyingthe dry coke coated particles discharged from the reaction space andremoving the larger size particles as the net coke product supplied tothe calcining operation.

4. The method as claimed in claim 3, including the step of bypassing apart of the removed larger size particles through a crushing operationto the reheating operation.

5. In a closed system for the continuous conversion of heavy residualoils into coke and lighter hydrocarbons by application of said oils to agravity packed downwardly moving column of preheated coke particles, thecombination comprising an upright reactor vessel having a particle inletat its upper end and a particle outlet at its lower end, means forfeeding heavy residual oil into the upper portion of the reactor vessel,means for withdrawing lighter hydrocarbons from the reactor vesseladjacent the oil feeding position, means for controlling the passage ofcoke particle through said particle outlet, an upright particle reheaterchamber, said reheater chamber having a particle outlet at its lower endconnected directly with the particle inlet of the reactor vessel,particle transfer. conduit means extending between the particle outletof the reactor vessel and the inlet of the particle reheater chamber, aproduct particle drawoif line in said transfer conduit means, a cokeparticle calciner bustion thus supplied.

6. In a closed system for the continuous conversion of heavy residualoils into coke and lighter hydrocarbons byapplication of said oils to adownwardly moving column of preheated coke particles, the combinationcomprising a vertical reactor Vessel having an inlet at its upper endand an outlet at its lower end, means for feeding heavy residual oilinto the upper portion of the reactor vessel, means for withdrawinglighter hydrocarbons from the reaction vessel adjacent the feedingposition, valve means for controlling the passage of coke particlesthrough said outlet, a vertical reheater chamber, said reheater chamherhaving an outlet at its lower end connected with the inlet of thereactor vessel, a particle classifier receiving all the coke particlesdischarged from the reactor vessel, said classifier being positionedabove said reheater chamber and adapted to separate the coke particlespassing from the reactor vessel into several sizes, a first line forfeeding particles of a desired size from the classi fier into the upperend of the reheater chamber, a second line for discharging particles ofanother size from the classifier for removal a product, a coke particlecrusher, a valved line connected to the second line and including saidcrusher for recycling any desired portion of said particles of anothersize from the classifier to a point between the outlet of the reactorvessel and the inlet to the reheater chamber, whereby the particles thusrecycled may be reduced to a suitable size for re-introduction to thesystem, a coke particle calciner of the combustion type connected insaid second line beyond said valved line, and. a third line for leadingthe hot gas produced in the calciner to the reheater chamber.

VERNON O. BOWLES. AUGUST H. SCHUTTE.

REFERENCES CITED The following references are of record in the file ofthis patent: V

UNITED STATES PATENTS

5. IN A CLOSED SYSTEM FOR THE CONTINUOUS CONVERSION OF HEAVY RESIDUALOILS INTO COKE AND LIGHTER HYDROCARBONS BY APPLICATION OF SAID OILS TO AGRAVITY PACKED DOWNWARDLY MOVING COLUMN OF PREHEATED COKE PARTICLES, THECOMBINATION COMPRISING AN UPRIGHT REACTOR VESSEL HAVING A PARTICLE INLETAT ITS UPPER END AND A PARTICLE OUTLET AT ITS LOWER END, MEANS FORFEEDING HEAVY RESIDUAL OIL INTO THE UPPER PORTION OF THE REACTOR VESSEL,MEANS FOR WITHDRAWING LIGHTER HYDROCARBONS FROM THE REACTOR VESSELADJACENT THE OIL FEEDING POSITION, MEANS FOR CONTROLLING THE PASSAGE OFCOKE PARTICLES THROUGH SAID PARTICLE OUTLET, AN UPRIGHT PARTICLEREHEATER CHAMBER, SAID REHEATER CHAMBER HAVING A PARTICLE OUTLET AT ITSLOER END CONNECTED DIRECTLY WITH THE PARTICLE INLET OF THE REACTORVESSEL, PARTICLE TRANSFER CONDUIT MEANS EXTENDING BETWEEN THE PARTICLEOUTLET OF THE REACTOR VESSEL AND THE INLET OF THE PARTICLE REHEATERCHAMBER, A PRODUCT PARTICLE DRAWOFF LINE IN SAID TRANSFER CONDIUT MEANS,A COKE PARTICLE CALCINER OF THE COMBUSTION TYPE CONNECTED IN SAIDPARTICLE DRAWOFF LINE, AND ANOTHER LINE CARRYING THE PRODEND OF THEPARTICLE REHEATER CHAMBER, SAID REHEATER CHAMBER BEING PROVIDED WITHMEANS BELOW SAID UPPER END FOR REMOVING THE PRODUCTS OF COMBUSTION THUSSUPPLIED.